What is the pOH of a 5.0 ×10-5 M hydrochloric acid (HCl) solution at 25° C?

Question

What is the pOH of a 5.0 ×10^-5 M hydrochloric acid (HCl) solution at 25° C?

Answer 1

pH + pOH = 14 (you should know this or memorize it)

pH = -log [H⁺]

5.0x10^-5 M HCl has [H⁺] = 5x10^-5 M, so pH = -log 5.0x10^-5 = 4.30

pH + pOH = 14

pOH = 14 - pH = 14 - 4.30

pOH = 9.70